SIZE Adult giant pandas range in body length from about 160 to 190 centimeters (64 to 76 inches). Males are slightly longer than females, have stronger forelegs, and are 10 to 20 percent heavier. In the wild males weigh from 85 to 125 kilograms (190 to 275 pounds), while females range between 70 and 100 kilograms (155 to 220 pounds). At birth, cubs weigh only 85 to 140 grams (3 to 5 ounces).

    HABITAT Giant pandas live at an altitude of between 1,200 and 3,500 meters (4,000 and 11,500 feet) in mountain forests that are characterized by dense stands of bamboo. Home ranges average 8.5 square kilometers (3.3 square miles) for ma les and 4.6 square kilometers (1.8 square miles) for females.

    DISTRIBUTION Pandas are found only in southwestern China , along the eastern edge of the Tibetan plateau. Although they were once more widespread, today they are limited to six small areas in Sichuan , Gansu , and Shaanzi provinces, totalling only 14,000 square kilometers (5,400 square miles).

    REPRODUCTION Pandas reach sexual maturity from four-and-a-half to six-and-a-half years of age and mate during the spring, from March to May. Females are in estrus for one to three weeks, but peak receptiveness lasts for only a few days. Litters of one, two, or occasionally three cubs are born in August or September, usually in a hollow tree or cave. Normally, only one cub is raised. Although cubs are usually weaned at about nine months of age, they remain with their mothers for up to 18 months.

    SOCIAL SYSTEM Except for females accompanied by cubs, giant pandas live a solitary existence. During the breeding season, several males may compete for access to a female. Home ranges of females are usually mutually exclusive, although they overlap occasionally, while the home range of each male may overlap those of several females. Pandas communicate by rubbing an acetic- smelling substance-secreted by glands surrounding the anogenital area-onto tree trunks and stones. They also scratch trees. Most territorial marking is thought to be done by males. Pandas are quite vocal and eleven distinct calls have been identified in the wild, although the function of each is not understood. In captivity, females vocalize during estrus as well.

    DIET More than 99 percent of the food consumed by giant pandas consists of the branches, stems, and leaves of at least 30 species of bamboo, the species eaten varying from region to region. Adults consume 12 to 15 kilograms (26 to 33 pounds) of food per day when feeding on bamboo leaves and stems. However, when feeding on new bamboo shoots, they are capable of eating up to 38 kilograms (84 pounds) per day, which is about 40 percent of their average body weight. Although the proportion is small, pandas also feed to a limited degree on other plants and a small amount of meat. They feed mainly on the ground but are capable of climbing trees as well. They are active mainly at twilight and at night.